As there are many paid tools available for checking your backlinks like Ahref, Moz, Semrush but there is a trick Semrush is currently working in their beta phase so just register with semrush and there is one Backlink Audit tool which will help you to identify the poor backlinks and this tool allows you to disallow the toxic domains easily.

Monitor Backlinks is an SEO platform that consolidates everything there is to know about your backlink profile and key SEO metrics. You can use it to monitor organic traffic, spy on competitor backlinks, check your rankings for specific keywords and more.

Which tool is the proper work to detect spammy backlinks and how to identify bad backlinks.

Thanks

Very good question but as far as I know there is no free tool available so far to detect which back links are spammy. you should identify by yourself which backlinks are spammy or not, If the backlinks are related from your niche then it is okay.

Having low-quality, spam backlinks pointing to your website is not only bad from a ranking point of view but it can also be extremely detrimental to the credibility of your brand. No business should want to have external references from untrustworthy, deceitful sources and this same mentality should transpire into your online.